Hand switch for controlling dental drilling machine drive



E. H. KOPP 3,244,846

HAND SWITCH FOR CONTROLLING DENTAL DRILLING MACHINE DRIVE April 5, 1966 Filed Nov. 1, 1961 United States Patent Ofiice 3,244,846 Patented Apr. 5, 1966 3,244,846 HAND SWITCH F04 C(DNTROLLING DENTAL DRILLING MACHINE DRIVE Erich Hermann Kopp, Pfalzgratenweiler, Wnrttemberg,

Germany, assignor to Siemens-Reiniger-Werke Akticngesellschaft, Erlangen, Germany Filed Nov. 1, 1961, Ser. No. 149,279 Claims priority, application Germany, Nov. 4, 1960,

3 Claims. 61. 20s 1s7 This invention relates to a control structure for a dental drilling machine drive with a drilling hand or angle piece capable of being withdrawn from a coupling part and includes an electric hand switch for controlling, switching on and off, regulating the speed, and reversing the direction of rotation of the drilling machine which may be an electric or a pneumatic drilling machine, and is directed particularly to the attachment and construction of the electric hand switch. By coupling part is to be understood either the drive end of the connection between a separate driving motor and the hand or angle piece, for example the link connection of a cord transmission running on small wheels which are mounted on interconnected mutually movable arms (Doriot link systern), or the connection piece of a flexible shaft, or the end of a flexible pressure medium feed tube for a compressed air motor arranged in the withdrawable hand or angle piece.

The switching on and ofi" as well as the regulation of an electric dental drilling machine is usually carried out with the foot on an electric switching and regulating device resting on the fioor. The objections to such a device are numerous and cause a considerable amount of annoyance to the denist. The foot switch is frequently not where it is required. The dentist is continually changing his position in relation to the patient and it repeatedly happens that the foot switch is not shifted when the dentist changes his position. Furthermore the body equilibrium of the dentist is rendered still more diflicult because he is obliged to transfer the weight of his body to one foot in order to operate the foot switch. The other foot must be free from weight in order to operate the foot switch and be able to react quickly. Such a cramped position of the dentist is very tiring and is not infrequently injurious to health.

It is therefore the object of the present invention to dispense with the foot switch and replace it by an electric switch which can be operated by the hand which holds the drilling hand or angle piece, without affecting the delicate holding and guiding of the hand or angle piece by manipulating the switch.

Owing to the known objections to the foot switch, various electric switches fitted on the hand or angle piece have already been proposed. As a rule, a relay which controls the high-voltage current circuit of the driving motor for the dental drilling machine, is controlled by a hand switch connected in a low-voltage circuit. The electric switches are arranged or fitted on the straight or angular drill hand piece, being in some cases rigid and in other cases axially and circumferentially shiftable.

The electric switches which are fixed on the drill hand or angle piece are open to the objection that many switches are necessary because every dentist requires several drill hand or angle pieces, namely both straight and angular hand pieces. Spare hand pieces must always be available when, for example, the one or the other drill hand piece is being sterilized, repaired or oiled. The sterilization of the electric switches fixed on the hand or angle piece presents difiiculties as the material from which they are made, for example insulating parts, feed wires and the like, cannot stand high temperatures. Moreover the electric switch fixed on the hand piece actually being employed must be first connected to the lead wires. If the switch is detachably mounted on the drill hand piece it must always be fitted when a hand piece is to be used or exchanged.

All this is very inconvenient and entails in the first case considerable expense and material and in the second case loss of time, with the result that known electric hand switches have not hithreto been introduced generally for drill hand pieces. Furthermore, it must be remembered that for carrying out the diiferent operations in the mouth of a patient either a straight or an angle drill hand piece is required. Very often the treatment of a tooth requires the alternate use of both instruments. This demands a rapid and reliable exchangeability of the drill hand piece fitted, for example, on a sliding connection piece of a Doriot link system or on a flexible shaft or on a flexible compressed air feed tube. If, however, the dentist has first to disengage the plug connections to the electric circuit of the switch and then to remove the switch from the hand piece before he can remove the hand piece in the usual manner in order to exchange it for an angle piece, and then again fit the switch on the angle piece, introduce the angle piece in the sliding connection piece of the Doriot link system and finally establish the electric connection to the switch, rapid exchange obviously is not possible. Moreover, it must also be mentioned that the electric hand switches usually are so large that they are in the way when working in the mouth cavity.

Consequently, the object of the invention is not only to do away with the foot switch, but also to overcome the disadvantages of the above-mentioned electric hand switches, and to provide a hand-operated electric device for controlling a dental drilling machine which is of extremely simple construction and so shaped that it neither impedes the usual finger position nor obstructs clear vision and reliable holding of the drill hand or angle piece during the drilling operation.

This problem is solved, according to the invention, by the provision of a dental drilling machine drive which comprises a drill hand piece and an electric hand switch for controlling electric or pneumatic drilling machines, the electric hand switch being fixed on a coupling part and its actuating member constructed as a depressible key carried by an arm extending freely from the coupling part substantially parallel to the longitudinal axis of the drill hand piece.

Two preferred embodiments of the invention will now be described by way of example and with reference to the accompanying drawing, in which:

FIG. 1 is a longitudinal section through a switch of electric insulating material, such as plastic, with an angle piece slipped on to the coupling part'ot an articulated sliding connection;

FIG. 2 is a longitudinal section of a switch produced from metal and fixed on the coupling part of a flexible shaft;

FIG. 3 is a top plan view of a switch on the hinge piece of an articulated sliding connection, with a hand piece slipped on to the coupling part of the articulated sliding connection, and

FIG. 4 is a cross-section taken on line IV-IV of FIG. 3.

FIG. 1 shows a switch which consists substantially of a switch body 1 made from insulating material, for example plastic. It may, however, also be made from metal. At its rear end it is bent at right angles in order to be fixed, according to the invention, on the hinge arm 13 of an articulated sliding connection by means of two screws 6 (FIG. 3). According to the invention the switch may be fixed on the coupling part of a flexible shaft or a pressure medium feed tube of a compressedair turbine-driven drilling machine, the rear end of the switch body 1 forms a mounting member which may be secured by two fixing screws on the coupling sleeve 15 of the flexible shaft (FIG. 2) or the pressure medium feed tube.

Such construction possesses the great advantage of the invention, namely: Entire independence of the difierent shapes and types of hand and angle pieces because the standard coupling part 14 is always freely accessible. The hand or angle pieces can be exchanged in a known manner easily and quickly and in spite of this the switch is always in the correct position for use.

Viewed from the side, the switch body 1 shown in FIG. 1 may be in the form of a bridge or arm, the rear end of the switch body forming one pier and reference numeral 12 indicating the other pier thereof. The pier 12 normally does not rest against the coupling part of the articulated sliding connection but is at such a distance therefrom that it allows the hand or angle piece to be slipped on easily. Only when a key 3 is depressed, does the pier 12 come into contact with the hand or angle piece and thereby carries out its function. This support or pier 12 may, however, be omitted entirely when the switch body is made from metal (FIG. 2). The mounting member formed by the rear end of the switch body 1 (FIG. 4) is clamped by screws 6 tightly against the coupling sleeve 15 of the articulated sliding connection, or against the sleeve 15 on the free end of the sheath of a flexible shaft (FIG. 2), or on the end of the pressure medium feed tube of a compressed-air turbine-driven dental drilling machine. The bridge or arm (FIG. 1) formed by the switch body 1 permits a stop spring 16 to slide through unhindered when the hand or angle piece is turned about its longitudinal axis to enable the hand or the angle piece to be brought into the desired position for working. For example, the drill head must point upwards when Working in the upper jaw and downwards when working in the lower jaw.

In the middle of the switch body 1 there is a slot-like guide passage 11 in which a resilient flat shank 2 of the depressible key 3 can slide. The flat shank 2 of the key 3 is fixed in its actual position by means of a spring 4 which may also form contact means. Notches 10 may be ground in the flat shank 2 of the key 3 at short intervals apart to enable the spring 4 to engage when the key 3 is extended or retracted. The whole shank 2 of the key is made of resilient conductive material, and at the front end of the flat shank 2 there is a key knob, for example of plastic, which serves as convenient rest for the finger.

By this arrangement it is now possible to vary the finger position in axial direction without difficulty because, as is known, the holding fingers are sometimes further forward and sometimes further backward on the hand or angle piece according to the work being carried out and the position necessary therefor. The fact that the switch is constructed as a push button switch, ensures an absolutely reliable finger position on the hand or angle piece, because the key 3, when in use, is depressed not only for contact-making on a contact spring 17, but preferably until it presses tightly against the sleeve of the hand or angle piece. Consequently, the dentist has his working instrument firmly in his hand in the customary manner and can also exert pressure on the material to be worked whenever necessary. This construction of the switch also enables the hand or angle piece to be firmly gripped and as a result the switching on of the drilling machine with the whole hand in order to carry out, for example technical grinding and drilling work in the dental laboratory, as well as in the consulting room.

The contact spring 17 arranged underneath the flat shank 2 of the key 3 is embedded in the switch body 1 and projects slightly therefrom. A wire leads from its rear end through the switch body 1 towards the rear end thereof and on passing out from the switch body 1 is connected with one conductor of a low-voltage cable 8 at a point indicated by reference numeral 7. The contact spring 17 projects a short distance so that when the key 3 is depressed it still comes into contact with the key 3 even when the key is extended to its limit. The contact spring 17 must be resilient to enable the key 3 to be pressed until it bears tightly against the sleeve of the hand or angle piece in any position.

The spring 4 is embedded in the switch body 1 above the fiat shank 2 of the press key 3. Another wire leads from the rear end of this spring 4, which thus also function as a contact, through the switch body 1 to the point 7 where it is connected to the other conductor of the lowvoltage cable 3. An aperture is provided in the top of the guide passage 11 in which the spring 4 engages with a downwardly bulged portion. The spring 4 may be fixed on the switch body 1 by means of screws 5. The aperture in the guide passage 11 enables the spring 4 to exert a pressure on the fiat shank 2 when the latter is in any position, the object being on the one hand to fix the key 3 and on the other hand to conduct current from one of the conductors of the low-voltage cable 8 to the flat shank 2 of the key 3.

By this arrangement the low-voltage circuit can be closed when the shank 2 of the key 3 is pressed on to the contact spring 17 and interrupted when the key 3 is released.

At the point 7 where the two wires pass out of the body 1, a plug connection may be provided for connecting up the low-voltage cable 8. The low-voltage cable 8 extends in a curve or loop at each of the joints of a link system and is secured in position with small holding clips on the connecting rods 9 before passing on. Alternatively, the connecting rods 9 may be hollow and the low-voltage cable 8 guided therein (FIG. 3), passing from one rod 9 to the next round the joints in a loop or curve. In this way the three joints of the link system with the cord guiding wheels can easily be bridged. The guiding of the low-voltage cable 8 within the connecting rods 9 is given preference for constructive and practical reasons.

The first connecting rod of the link system is the dental arm of the drilling machine. The low-voltage current wires can also pass through the dental arm and lead from there to a switch relay which in turn controls the highvoltage circuit of the drilling machine. The low voltage for operating the switch relay can be taken from the dental unit in which there is in any case a source of lowvoltage current.

The path of the low-voltage current can easily be followed with the aid of FIG. 1 of the drawing. The current is fed by one conductor of the low-voltage cable 8 to the point 7 and thence through the switch body 1 to the spring 4, where it is conducted to the flat shank 2 of the key 3 and, when the key 3 is pressed onto the contact spring 17, can flow back through the switch body 1 to the position 7 and thence finally to the other conductor of the low-voltage cable 8.

It might also be possible to provide only one conductor in the low-voltage cable 8 and to use the mass for the return path. However, this method is not employed in the present-embodiment because the joints of the link system do not make perfect contact as they are oiled and any current flow in the hand or angle piece should be avoided.

The control of the speed and direction of rotation of the motor can be effected in various ways. In the form of construction described, a potentiometer and a doublepole commutator, together with the relay, may be disposed in a box fixed on the stand or instrument cupboard which is situated on the left of the dentist. In this manner the dentist can easily regulate the speed of the drilling machine infinitely variable with his left hand by means of a knob on the box and control the direction of rotation by merely reversing the commutator or throw-over switch, should this be necessary. The potentiometer is, however, normally set to a working speed which suits the dentist.

It is evident that the control of the dental drilling motor might also be effected by an electromagnetic amplifier and the small control resistance in the control circuit of the magnetic amplifier might be arranged in the switch body 1 so as to enable the speed of the motor to be easily controlled from the switch body 1 in addition to the switching on and off of the motor.

Another solution might consist in building a push-button control in the switch body 1 in such a manner that one push-button determines the direction of rotation of the drill through the intermediary of a relay and a second push-button influences a step-relay which in turn controls the number of revolutions of the drilling machine stepby-step. The resistance and relay necessary for this purpose can be built in the unit so as to give a good appearance.

The electromagnetic switching relays could also be controlled by electronic low-stage modulation so that in the control circuit thereof and consequently in the switching elements to be manipulated by the dentist, very minimal voltages, mostly less than one volt, would be present, with the result that the insulating conditions could be simplified and at the same time a contact protected control attained.

It has already been mentioned that the above-described switch body of the construction in question can also be made from metal. In this case one conductor of the lowvoltage cable 8 can be connected to the mass of the switch body 1 at point 7 (FIG. 2) while only the other conductor is insulated from the mass and leads through the switch body up to the contact spring 17 which is also insulated from the mass at 18 and fitted in the switch body,

The hand switch, of extremely simple construction, is fitted neither on the hand piece nor on the angle piece, but on an arm of the sliding connection of a Doriot link system, on the end of the drill tube of a flexible shaft, or on the end of the pressure medium tube of a compressed-air turbine-driven dental drilling machine. In the last instance the depressible key switches the compressor on and off. By this arrangement the decisive advantages of the invention are achieved, namely: complete independence of the type and shape of the hand and angle pieces which are used, quick and reliable exchange of the hand and angle pieces in a known manner, possibility of axially extending the finger key to suit any finger position on the hand or angle piece, possibility of turning the hand or angle piece about its longiudinal axis in a known manner by bridging the coupling part including the stop spring, absolutely reliable grip when holding the hand or angle piece in the fingers as the key is depressed until it is in contact with the sleeve of the hand or angle piece at each switching in operation, while at the same time maintaining the customary finger position, and effecting speed regulation and control of direction of rotation from the hand switch by suitable constructional measures.

The invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The present embodiments are therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description and all changes which come within the meaning and range of equivalency of the claims are therefore intended to be embraced therein.

I claim:

1. A control structure for dental drilling machine drives, having a drill hand piece which is movably mounted on a mechanical coupling part for the transmission of drive energy thereto, comprising an electrical switch for operatively controlling such drive energy, said switch having a mounting member constructed for operative attachment to such a coupling part, an arm. extending from said mounting member in freely self-supporting manner substantially parallel to the longitudinal axis of such a drill hand piece, and a manually operable switch actuating member supported by said arm and extending from the free end thereof, said switch actuating member being longitudinally adjustable relative to said arm.

2. A control structure as defined in claim 1, wherein said switch actuating member comprises a metallic member slidably disposed in a cooperable passage in said arm, and forming a contact element of the switch, and a cooperable contact element disposed adjacent said switch actuating member and operatively engageable therewith when the latter is manually operated.

3. A control structure as defined in claim 2, comprising a metallic spring member engageable with said switch actuating member for operatively retaining the same in any of its adjusted positions, said spring member providing means for operatively electrically connecting said switch actuating member in an electrical circuit to be controlled.

References Cited by the Examiner UNITED STATES PATENTS 1,266,420 5/1918 Dean 200-l57 2,664,632 1/1954 Norlen. 2,681,408 6/1954 Bronk 32-28 RICHARD A. GAUDET, Primary Examiner.

ROBERT E. MORGAN, Examiner. 

1. A CONTROL STRUCTURE FOR DENTAL DRILLING MACHINE DRIVES, HAVING A DRILL HAND PIECE WHICH IS MOVABLY MOUNTED ON A MECHANICAL COUPLING PART FOR THE TRANSMISSION OF DRIVE ENERGY THERETO, COMPRISING AN ELECTRICAL SWITCH FOR OPEATIVELY CONTROLLING SUCH DRIVE ENERGY, SAID SWITCH HAVING A MOUNTING MEMBER CONSTRUCTED FOR OPERATIVE ATTACHMENT TO SUCH A COUPLING PART, AN ARM EXTENDING FROM SAID MOUNTING MEMBER IN FREELY SELF-SUPPORTING MANNER SUBSTANTIALLY PARALLEL TO THE LONGITUDINAL AXIS OF SUCH A DRILL HAND PIECE, AND A MANUALLY OPERABLE SWITCH ACTUATING MEMBER SUPPORTED BY SAID ARM AND EXTENDING FROM THE FREE END THEREOF, SAID SWITCH ACTUATING MEMBER BEING LONGITUDINALLY ADJUSTABLE RELATIVE TO SAID ARM. 